17 February 2016: Thanks to Nkechi Ogwo, Ugochukwu N. Ikeogu, and Lilian A. Onyegbulam of the NextGen Cassava Project for the following write-up of a recent visit by NextGen students to test NIRS tools in cassava breeding:
The NextGen Cassava Project has taken significant strides to address the challenges of long breeding cycles in cassava improvement by adopting advanced breeding tools; notably, genomic selection (GS). Efficient implementation of GS in various breeding programs requires informative genotype data as well accurate and fast phenotyping tools. In addressing the phenotyping bottleneck at National Root Crops Research Institute (NRCRI), Umudike breeding program, Dr. Chiedozie Egesi, an Assistant Director, Plant Breeder, and Coordinator of the Programme acquired a hand-held version of the NIRS (Near-Infrared Spectroscopy) device for cassava breeding at the institute. This was supported by the Next Generation Cassava Breeding Project being funded by the Bill & Melinda Gates Foundation.
NIRS is a long-established technology commonly used to estimate organic constituents such as protein, starch, oil, and carotenoid in numerous agricultural products. The NIRS technology is built on the interaction of physical matter with the near-infrared spectral region of light. The sampling process involves the irradiation of a sample with light of specific known frequency or wavelength in the near-infrared region. The estimation of frequency at which specific bonds vibrate enables NIRS instruments to predict from a spectrum the composition of the molecular bonds present in a given sample. The technology has been designed in various forms and shapes.
When compared to the traditional methods of organic components assay, such as the I-check carotene and high performance liquid chromatography (HPLC), NIRS has huge advantages. It is unusually faster than other analytical techniques. For example, for some it takes more than one day to complete the extraction of some organic components and, depending on the system, it might only accommodate fewer than 30 samples for a complete cycle. Conversely, NIRS devices can be used to sample between 500 and 900 samples in a day. The technique is non-destructive and only simple preparation, or no preparation at all, is required of samples. In the case of the hand-held version acquired by NRCRI, Umudike, the instrument can be used directly in the field, which eliminates almost completely the difficulty of sample preparation and transportation. The device is very versatile and can be used for the analysis of several traits simultaneously. More so, NIRS avoids high hazards and problems of organic and other chemical waste disposal that are likely associated with other techniques.
The adoption of this device in phenotyping became necessary because the recent adoption of GS hinged on recent advances in molecular marker technologies with the unprecedented assay of many genetic materials associated with the technologies.
The preliminary field application and chemometric process for quantifying important cassava root parameters—namely, starch, dry matter, carotenoid, and cyanide—took off in summer 2015 in NRCRI’s breeding program. The team is led by one of the PhD students, Ugochukwu Ikeogu from Cornell University, Ithaca, USA. For prospective extension of the technology to other breeding programs across Africa, a representative, Mr. Wilfred Abincha Magangi, who is a Master’s student from Makerere University, Uganda, East Africa visited Nigeria to witness the field application of the device.
The adoption of NIRS devices in cassava root component assay promises to increase the accuracy and efficiency of phenotyping and further hasten cassava breeding efforts being undertaken by the biotechnology program of NRCRI, Umudike.
Relating his experiences at the institute, Mr. Magangi during his two-week study visit shared that over and above accommodating huge samples per day, NIRS could be one of the most efficient tools for phenotyping in cassava breeding programmes. It is easy to handle, saves time and costs, and at the same time generates accurate results, as opposed to the other conventional tools used in East Africa. He also added that the NIRS device is less expensive to maintain.
The field visits and facility tour presented a knowledge exchange and networking opportunity for both groups. Mr. Magangi, the visiting student from Makerere University, Uganda said, “this experience has been an eye opener; learning a better way to phenotype by trying this unique tool for the first time, communicating with colleagues from West Africa, and learning from their experiences will help East Africa in the future.” It could be anticipated that this huge improvement in cassava breeding will go a long way to reduce the length of cassava breeding cycles and foster early release of improved varieties towards food security. Based on its numerous advantages, one could tell that the adoption of the NIRS tool in Africa is an environmentally friendly and accuracy-enhancing option for cassava breeding programmes when compared with the traditional phenotyping techniques.
This study visit forms part of a wider capacity building initiative of the NextGen Cassava Project.